I feel like certain organizations don't allow open face helmets on track. I like the added protection of full face - ive had things fly into the cabin before while on track (rubber, rocks, etc) and prefer the extra safety I have.

I had a piece of rubber hit me in the eye with my face shield up. Luckily I was riding shotgun because it hurt and screwed up my vision for a few minutes.

Now I always keep the shield down or at most slightly cracked for ventialtion. I've heard that leaving your face shield up is dangerous because the airbag can grab it and whip your head back. Not sure how true it is but just another consideration.

I'd prefer the full face just for debris on track days. An open face helmet is probably fine for just autox though.

In an Instructor seminar last Spring - I saw a brief presentation about running helmets with visors in cars with airbags. The concern was in an impact - the airbag catching the edge of an open visor and violently rotating the helmet backward (rotating bottom-to-top) as the airbag inflates. This was apparently driven by real-world incidents.

The guidance/recommendation was to have the visor open no more than two fingers (index and middle) wide.

Here in NJ, the law will soon mandate closed face helmets. It actually already does but there is a temporary exemption in one case I know of. I've heard about the face shield issue with airbag deployment and this is a concern. Some of us wonder whether closed face with visor removed might be the best answer for HPDE.

In the end, there's always going to be some risk. I use a closed face myself, but I do leave the visor open. Maybe not ideal.

As others have said, closed face mostly for debris and also to add lower face protection in the event of a crash / airbag deployment. I have both and tried the open face during the last track day but had a couple scares with rocks coming in and will stick with the full face from now on.